#include<bits/stdc++.h>
#define ll long long
#define L x<<1
#define R x<<1|1
#define mid ((l+r)>>1)
#define lc L,l,mid
#define rc R,mid+1,r
#define Root 1,1,n
#define OK Ll<=l&&r<=Rr
#define rep(x,y,z) for(int x=(y);x<=(z);x++)
#define per(x,y,z) for(int x=(y);x>=(z);x--)
#define repn(x) rep(x,1,n)
#define repm(x) rep(x,1,m)
#define pb push_back
#define e(x) for(int i=h[x],y=to[i];i;i=nxt[i],y=to[i])
#define E(x) for(auto y:p[x])
#define Pi pair<int,int>
#define ui unsigned ll
#define yy puts("Yes"),exit(0)
#define nn puts("No"),exit(0)
#define YY return puts("Yes"),void()
#define NN return puts("No"),void()
inline int read(){int s=0,w=1;char c=getchar();while(c<48||c>57) {if(c=='-') w=-1;c=getchar();}while(c>=48&&c<=57)s=(s<<1)+(s<<3)+c-48,c=getchar();return s*w;}
inline void pf(int x){if(x<0) putchar('-'),x=-x;if(x>9)pf(x/10);putchar(x%10+48);}
using namespace std;
const int N=2e5+5,M=1e6+5,inf=(1LL<<30)-1,mod=1e9+7;
const ll llf=1e18;
inline void add(int &a,int b){if(b<0)b+=mod;((a+=b)>=mod) and (a-=mod);}
inline int Add(int a,int b){return add(a,b),a;}
inline int mul(int a,int b){add(b,mod);return 1LL*a*b%mod;}
inline void Mul(int &a,int b){a=mul(a,b);}
inline void red(int &a,int b){add(a,mod-b);}
inline int Red(int a,int b){return red(a,b),a;}
inline int qp(int a,ll b){if(!b)return 1;int c=qp(a,b>>1LL);Mul(c,c);if(b&1)Mul(c,a);return c;}
inline int INV(int x){return qp(x,mod-2);}
inline bool che(int x,int p){return (x>>p)&1LL;}
int n,a[N],m;
struct seg{
	int sum[4][3],mx[4][3],ans[4][3];
}xd[N<<2];
inline seg getup(seg a,seg b){
	seg c;
	rep(S,0,3)rep(mx,0,2){
		int SS=a.sum[S][mx],Mx=a.mx[S][mx],AA=a.ans[S][mx];
		c.sum[S][mx]=b.sum[SS][Mx],
		c.mx[S][mx]=b.mx[SS][Mx],
		c.ans[S][mx]=AA+b.ans[SS][Mx];
	}
	return c;
}
inline void build(int x,int l,int r){
	if(l==r){
		int w=a[l];
		rep(S,0,3)rep(mx,0,2){
			if(S>=w){
				xd[x].sum[S][mx]=S-w,xd[x].ans[S][mx]=1,xd[x].mx[S][mx]=max(mx,w);
			}else {
				if(mx>w){
					xd[x].sum[S][mx]=S+mx+mx-w,xd[x].mx[S][mx]=mx;
				}else {
					xd[x].sum[S][mx]=S+w,xd[x].mx[S][mx]=mx;
				}
			}
		}
		return;
	}
	build(lc),build(rc),xd[x]=getup(xd[L],xd[R]);
}
inline seg query(int x,int l,int r,int Ll,int Rr){
	if(OK)return xd[x];
	if(Rr<=mid)return query(lc,Ll,Rr);
	if(Ll>mid)return query(rc,Ll,Rr);
	return getup(query(lc,Ll,Rr),query(rc,Ll,Rr));
}
inline void Main(){
}
signed main(){
	// freopen("a.in","r",stdin);
	// freopen("a.out","w",stdout);
	int T=1;
	while(T--)Main();
	return 0;
}
